One of the most powerful imaging instruments of our time recently captured the first-ever nova explosion of a dead star. The photo was collected with the help of astronomers from Russia and Germany.
Russia-Germany eROSITA Instrument Gets X-Ray Photo of YZ Reticuli Nova
Fig. 1: Sky images of all seven eROSITA cameras combined (0.2–0.6 keV).
The telescope utilized for the project was the eROSITA x-ray instrument aboard the Spektr-RG observatory. The device is currently located at the planetary orbit's L2 Lagrange point, which is the same satellite neighborhood as the recently launched James Webb Space Telescope.
The nova explosion is considered the 'fireball' phase of stars when they die. The x-ray image that was captured from the event was carried out through a scientific prediction that was presented back in the 1990s.
The nova is named the 'YZ Reticuli,' and was initially detected back on July 15, 2020. The origin star of the phenomenon was charted at approximately 8,250 lightyears and south of the Reticulum constellation.
Experts categorize the new star explosion as a 'classical nova,' which is commonly displayed by white dwarfs during the last few phases of their lifetime.
The eROSITA telescope stumbled upon the nova while on a wide scale survey project between June to December of 2020. The region where the nova sits was scanned multiple times by the instrument. Over the course of 22 passes, the nova appeared normal, but on the 23rd scan, the orb was found to shine abnormally bright.
Through x-ray imaging technique, the explosion was discovered to have come from the YZ Reticuli. However, its luminance fluctuated and eventually disappeared on the following pass. Experts concluded that the flash occurred in just less than eight hours, Science Alert reports.
Fireball Phase Theory Confirmed
In the study, analysis shows that the event was a completely separate stage of nova, called a fireball, that occurs as a result of a stellar eruption.
The 1990 prediction explained that the fireball phase commences between the runaway fusion that starts the explosion and the brightness of the star that is emitted with intense optical wavelengths.
The phase, according to the theory, appears as short and soft, but bright flash x-ray radiation right before the optical wavelengths of the stellar emissions reaches their maximum brightness.
The fireball phase happens due to the expansion of the star's materials, as it briefly touches the surface or photosphere of the white dwarf. This step happens with an extreme outward acceleration that already parallels the inward pull of the gravity. The white dwarf will then heat up and give out its peak beam known as the Eddington luminosity.
The explosion then cools down as it expands further. The brightness displayed by the dead star would turn the energetic x-ray wavelengths into an optical type, allowing observers to perceive the nova explosion.
Due to the eROSITA's successful capture of the YZ Reticula's image, experts conclude that the existence of the x-ray flashes is now 'observationally confirmed.'
The study was published in the journal Nature, titled "X-ray detection of a nova in the fireball phase."
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